94 Grand Cherokee 5.2 240,000mi
so my jeep died on the freeway and got it towed home. I was checking it out today and theres no spark coming from the plugs, but if i hold a rachet up to the coils terminal and something else metal i get a very slight shock, not like the usual painful jolt but there is a weak spark from the coil. if i put i plug wire and spark plug hooked directly up to the coil there is no spark.

this makes me think he crank position sensor isnt at fault plus i didnt get a check engine light and it would have been code 55 or 54 for no signal from cps.

i just changed the cap and rotor anyways but the weak spark is coming from the coil itself so anything else i should check before replacing the coil?
would i still get a slight spark with a bad crank sensor?

(new plugs, wires, cap rotor, ecu, within the last 20k miles)

thanks

loudrango

07-08-2009, 10:21 PM

how old is your battery and alt?and are the terminals cleaned good?if your battery is getting weak it doesn't supply enough current to the sensors,ecu,etc causing them to act up there having your truck stall out.been around mopar motors for years.i'd check those out bro.get a load test put on the battery and alt.also on earlier mopars you can turn the key on and off 4 or 5 times without starting it and it will flash codes on the check engine light.

BoxdGM

07-09-2009, 01:25 AM

new battery and terminals and i dont have any check engine trouble codes stored

DBfan187

07-09-2009, 11:13 AM

CPS is dead, mine's the same way. Only problem I have with it is actually getting to it to replace it.

BoxdGM

07-09-2009, 03:36 PM

if the cps was dead would i still have voltage to the coil? i thought no voltage to the coil means bad cps.

jdawg

07-09-2009, 03:42 PM

did you pull any codes? I know you say the light isnt on but there may be codes. I have sold pick up plates for those also

BoxdGM

07-09-2009, 03:46 PM

all i got was power lost within the last 20-30 starts and the code for end of diagnostic mode, and i had to pull the battery to remove the coil the check its resistance

jdawg

07-09-2009, 04:01 PM

there isnt much left other than the cs, coil, plate in the dist, and wiring. Did you pull the cap, have someone hit the key and make sure the rotor is turning?

BoxdGM

07-09-2009, 05:27 PM

there isnt much left other than the cs, coil, plate in the dist, and wiring. Did you pull the cap, have someone hit the key and make sure the rotor is turning?

just changed the coil and starts right up now. thank god it wasnt a cps problem since those are a PITA to replace on a 5.2. Progressive FTW they let me add roadside assistance to my policy from the side of the highway then connected me to roadside assist and sent out a tow truck. all i had to pay was $4 for 6 months of free towing, beats a +200$ 20mile tow charge

thnks everyone for the input, i got more help here than on the jeep forums

BoxdGM

07-09-2009, 05:31 PM

CPS is dead, mine's the same way. Only problem I have with it is actually getting to it to replace it.

have you checked to see if you have voltage at the coil electrical connector?